Anatomical study of the Iranian brown bear's skull (Ursus arctos): A case report

The Brown bear (Ursus arctos) is a species at risk of extinction. It is considered the largest carnivore and lives in northern Iran. Several studies on the structure of skull have been accomplished in different animals. The aim of this study was the inscription of gross anatomical characteristics of skulls of three Iranian adult male brown bears that were transferred to the Anatomical Department of the Faculty of Veterinary Medicine of Semnan University. After processing, that included cleaning, degreasing and bleaching, skulls were studied from the dorsal or frontal, ventral, lateral, rostral, caudal and medial views. The facial part of the brown bear’s skull from dorsal view was small and the cranium was seen quadrilateral and larger than the dogs. The facial part of lacrimal bone and also the optic groove of presphenoid were absent. There was not articulation between maxillary and nasal bones. The interincisive canal was present and situated inter palatine processes of incisive bones. The orbital cavity was small in brown bear. Lacrimal canal was formed by lacrimal and maxillary bones. The interparietal bone and external sagittal crest in brown bear were seen as being shorter than the dogs. Tympanic bulla was very small and jugular foramen rounded. The external acoustic meatus was formed by squamous and tympanic part of temporal bone. In conclusion, the brown bear’s skull has different important macroscopic characteristics compared to other carnivores.